Portable winch

ABSTRACT

A portable winch suitable for use in underground pipe bursting and replacement includes a mounting frame positionable at a top opening of a hole such as a receiving pit or manhole. A telescoping mast having a series of nested, top and bottom mast sections is mounted on the frame. A powered winch unit, also mounted on the frame, includes a drive unit and a cable. A guide assembly includes a sheave that guides the cable from the drive unit to the bottom mast section. Suitable means are connected to the frame for mechanically raising and lowering the mast into and out of the hole. As such, the mast according to the invention does not require assembly or disassembly at the beginning and end of each job. The mechanical means for raising and lowering the mast is preferably the powered winch unit.

RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.:11/438,568, filed May 22, 2006, pending, which is a continuation of U.S.application Ser. No. 10/666,592, to Wentworth et al., filed Sep. 19,2003, now U.S. Pat. No.: 7,048,257, Issued May 23, 2006.

FIELD OF THE INVENTION

This invention relates to winches for pulling cables, particularly aportable winch used to pull an underground conduit during a pipeinstallation or replacement operation.

BACKGROUND OF THE INVENTION

The process of pipe bursting to replace buried frangible pipes has beenin commercial existence since the late 1980's. While originallydeveloped with the intent of replacing cast iron natural gas pipelinesin Europe, it is of great promise within the continental U.S. to remedyproblems with sewer systems.

Our sanitary sewer systems are constantly a source of contamination forfreshwater ecosystems. Ground water, present in great abundance afterrainfall around sewer pipes actually enters the sewer system. It willenter the system as it has ingress through gaps, fractures and otherleaks in the old and deteriorated pipes present in all older systems. Byentering the sanitary system, the groundwater must be treated assanitary waste.

Unfortunately, the rate of inflow of groundwater after a rainfall isoften 2 to 4 times the systems normal flow rate. When this happens, theprocessing rate can't keep up with the inflow rate, the untreated sewagemust be discharged back into the ecosystem, normally finding it's way toa freshwater lake or stream. It is after this type of event that ‘NoSwimming’ signs are posted at beaches and other warnings are made bynews media about raw sewage flowing into water ways.

There are four remedies for this problem. The first is traditional opencutting, digging of open trenches to replace the old leaking pipes. Ithas an excellent end product, however it involves massive disruption onthe surface and is generally an unpopular solution. The second involvesdigging of ‘deep tunnels’, nothing more than storage caverns for excessflow that is intended to be treated at a later date. This works untilrain storms occur back to back and the capacity is exceeded. Inaddition, the condition or leak rate of the sanitary system is alwaysincreasing as the pipes age.

The third and fourth methods are variations of each other. In lining,whether cured in place pipe (CIPP) or slip lining, the pipe istemporarily patched. It stops the leak for a period of years, but ingeneral it is a ‘spot’ repair, or nothing more than a thin liner. It isinevitable that the process will have to be undertaken again when thenext aging joint in the system begins to open and permit leakage.

The fourth method, the most permanent, most adaptable and unquestionablythe overall preferred method, is pipe bursting and replacement ofsanitary sewer systems. It produces a brand new pipe with superior lifeand sealing capability. It is a trenchless process much as CIPP orlining is, producing little surface disruption; however, it has sufferedthe drawback of involving more physical labor than lining.

The present invention provides a device that reduces the amount ofphysical labor required to perform pipe bursting of sanitary sewersystems. Such a process most typically uses a pneumatic impact device tohammer a mole through the existing pipe and expand the surrounding soil.This mole is commonly attached to the HDPE (high density polyethylene)product pipe that becomes the new, leak proof pipe system. The mole ispulled through the old pipeline by a winch mounted at the receiving endof the line, with or without use of an impactor in addition to thepulling force exerted by the winch.

In many processes, a pneumatic impact hammer is used as the mole. Tomaintain progress of a pneumatic hammer towing a string of plasticreplacement pipe, the hammer is normally guided by a wire rope drawn bya constant tension winch. The winch is at ground level, with a mast thatextends downward from the winch into either a small excavation, or morelikely a sewer manhole. This mast is a hollow tube through which thewire rope passes to reach the subterranean level of the pipe. Afterchanging direction 90 degrees around a sheave, the wire rope will enterthe pipe and traverse the entire length of the pipe to be burst andreplaced.

The constant tension winch has the formidable task of keeping suitabletension (in this case 24,000 lb) on the wire rope, and winding the wirerope for storage between jobs while functioning with the mast and sheavedescribed earlier. In addition, the unit must be mobile. Upon completionof a section of pipe bursting (typically 500 feet), the winch must moverapidly to the next section. It is desirous, but has not been the case,that setup and teardown of the winch and mast should be rapid and with aminimum of effort. This invention addresses that aspect of the process,and in doing so, makes the process of pipe bursting more efficient, morecost effective and more likely to be chosen as a rehabilitation methodover other methods described.

Previous designs involved the assembly of mast sections on the surface,then lowering the mast into position using a lifting device such as asmall mobile crane. After the mast was in position in the manhole, thewinch was brought into place and the mast attached to the winch. Uponcompleting this, the wire rope was threaded through the hollow sectionsto the sheave. At this point the unit would be considered ‘set up’. Theprocess was performed in reverse to remove the winch upon completion ofa pull.

Winches currently in use for underground pipe replacement generallyinclude the Hydroguide series of winches sold by Vermeer. Handford U.S.Pat. No. 5,328,297 describes a pipe replacement system using a winchwherein the winch mast is deployed by lowering one of a pair of nestedmast sections. This represents an advance over systems requiringcomplete manual assembly, but the job of deploying the mast and removingit when the job is completed is still a manual task.

SUMMARY OF THE INVENTION

A portable winch according to the invention suitable for use inunderground pipe bursting and replacement includes a mounting framepositionable at a top opening of a hole, a telescoping mast including aplurality of hollow, nested, top and bottom mast sections, a mountingassembly by which the top mast section is secured to the mounting frame,a powered winch unit mounted on the frame, including a drive unit and acable, positioned so that the cable can be fed into the telescopingmast, and mechanical means connected to the frame for raising andlowering the mast into and out of the hole by collapsing anduncollapsing the telescoping mast while it is secured to the mountingframe. As such, the mast according to the invention does not requireassembly or disassembly at the beginning and end of each job. Themechanical means for raising and lowering the mast is preferably thepowered winch unit, but other possible systems are discussed hereafter.

According to another aspect of the invention, that mast is mounted onthe frame so that it can be pivoted from a storage position to anoperating position and back again. Such a portable winch includes amounting frame positionable at a top opening of a hole, a pivot mountedon the frame, a telescoping mast including nested, top and bottom mastsections, mounted to the frame by the pivot, a powered winch unitmounted on the frame, including a drive unit and a cable, a guideassembly including a sheave that guides the cable from the drive unit tothe bottom mast section, and suitable means for releasably securing aleading end of the cable to the bottom mast section. By this means, themast can be lowered into the hole beneath the frame by pivoting the mastinto position for lowering, connecting the leading end of the cable tothe mast, and then operating the winch unit to lower a bottom section ofthe mast. The mast can be raised out of the hole by connecting theleading end of the cable to the bottom mast section and pulling thecable with the winch unit to collapse the telescoping mast.

A method for installation of an underground pipe according to theinvention using a portable winch such as the foregoing includes thesteps of:

positioning a mounting frame of the portable winch at a top opening of ahole;

pivoting a telescoping mast including nested, top and bottom mastsections, which mast is mounted to the frame by the pivot, from ahorizontal position to a vertical position;

lowering the bottom mast section into the hole by operating a mastcontrol system that includes a mast cable and a mechanism that graduallypays out the mast cable to lower the bottom mast section;

securing the mast in the hole for horizontal pulling using a pullingcable wound over a sheave mounted on the mast;

feeding the pulling cable through a pipeline adjoining the hole andsecuring a pipe bursting mole having a replacement pipe attached to thecable;

operating a powered winch unit mounted on the frame to pull the pullingcable, mole and replacement pipeline through the pipeline in order toburst the pipeline and replace it with the replacement pipe;

unsecuring the mast in the hole so that is can be removed from the hole;

raising the bottom mast section up from the hole by operating the mastcontrol system to gradually pull the lower mast section upwardly; and

pivoting the mast about the pivot from a vertical position to ahorizontal position.

These and other aspects of the invention are discussed in the detaileddescription that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawing, wherein like numeral denote like elements:

FIG. 1 is side view of a portable winch unit according to the inventionin a storage position;

FIG. 2 is a top view of the winch shown in FIG. 1;

FIG. 3 is a rear end view of the winch unit shown in FIG. 1;

FIG. 4 is a side view of the winch unit shown in FIG. 1 with housing andcomponents removed to show the cable pulling mechanism;

FIG. 5 is a perspective view of the winch unit shown in FIG. 1, with thehousing removed;

FIG. 6 is a top view of the winch unit shown in FIG. 5;

FIG. 7 is a partial rear view of the winch unit of FIG. 1 with the mastin its deployed position;

FIG. 8 is a partial, right side lengthwise sectional view of the cablepulling mechanism of the winch unit of FIG. 2 with the mast stowed;

FIG. 9 is a partial, right side lengthwise sectional view of the cablepulling mechanism of the winch unit of FIG. 2, with the mast deployed;

FIG. 10 is a partial, left side lengthwise sectional view of the cablepulling mechanism of the winch unit of FIG. 2, with the mast deployed;

FIG. 11 is a partial, left side perspective view of the cable pullingmechanism of the winch unit of FIG. 2, with the mast deployed;

FIG. 12 is a perspective view of the winch unit shown in FIG. 1, withthe mast deployed;

FIG. 12A is an enlarged view of the mast holding mechanism shown in FIG.12;

FIG. 12B is a top view of the mast holding mechanism shown in FIG. 12A;

FIG. 13 is a rear view of the upper mast joint shown in FIG. 12;

FIG. 14 is the same view as FIG. 13, with the top mast in lengthwisesection;

FIG. 15 is a left side view of the upper mast joint shown in FIG. 12;

FIG. 16 is a right side lengthwise sectional view of the upper mastjoint shown in FIG. 12;

FIG. 17 is a rear perspective view of the foot assembly shown in FIG.12;

FIG. 18 is a top view of the foot assembly shown in FIG. 17;

FIG. 19 is a side view, partly in section, of the foot assembly shown inFIG. 12;

FIG. 20 is a partial, front perspective view of the foot assembly shownin FIG. 12;

FIG. 21 is a cross sectional view taken along the line 21-21 in FIG. 18;

FIG. 22 is a partial top view of the foot and mast assembly of FIG. 12,with the mast in cross section;

FIG. 23 is a side view of the foot assembly of FIG. 12, with the legs instowed position;

FIG. 24 is a rear perspective view of the frame of the of the footassembly of FIG. 12;

FIG. 25 is a side view of the frame of the of the foot assembly of FIG.24;

FIG. 26 is a sectional view taken along the line 26-26 in FIG. 25;

FIG. 27 is a sectional view taken along the line 27-27 in FIG. 25;

FIG. 28 is a partial rear view according to an alternative embodiment ofthe invention showing the top of the upper mast;

FIG. 29 is a partial rear view at the lower end of the upper mast shownin FIG. 28;

FIG. 30 is a partial side view of the lower end of the upper mast shownin FIG. 29;

FIG. 31 is a partial side view according to a further alternativeembodiment of the invention showing the top of the upper mast; and

FIG. 32 is an enlarged, partial rear view of the upper mast shown inFIG. 31.

In the drawings, welded connections between parts secured rigidlytogether are used unless noted otherwise. Fluid hoses for hydraulicfluid are omitted for clarity.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIGS. 1-6, a portable winch unit 21 according to theinvention includes a frame 22 such as a trailer which can be pulled to asite by means of a trailer hitch 23 and tires 24. A vehicle housing 26covers the winch mechanism 27. Front and rear jacks 28, 29A and 29Bmanually operable by means of cranks 31 permit the unit to be securelymounted on the ground once the job site has been reached. A telescopingmast assembly 32 is stowed horizontally in a collapsed position over thetop center of housing 26 and secured thereto by a latch mechanism 33.Mast assembly 32 has a collapsible foot assembly 34 at its distal(bottom) end which is deployed as described hereafter once thetelescoping mast has entered the hole adjoining the pipeline to beburst.

FIGS. 3-6 show details of winch mechanism 27. A storage spool 36 for awire rope (not shown) is mounted towards the front of frame 22 and isdriven to wind the rope by a hydraulic motor 37 that drives a sprocket38 by means of a drive sprocket 39 and chain (not shown.) In thisembodiment, hydraulic motor 37 is powered by means of hydraulic fluidprovided through hoses (not shown) from a hydraulic pump 41. Pump 41 ispowered by means of a diesel engine 42 and receives hydraulic fluidthrough hoses from a reservoir 44. Motor 37 is designed to provide aconstant pulling force sufficient to keep the wire rope in tension. Awinding guide 43 assures even winding of the cable onto spool 36 duringpullback.

A dual capstan drive unit 46 is powered by a hydraulic motor 47 thatreceives hydraulic fluid from pump 41. Motor 47 is provided with aplanetary gear reducer 48 for driving a central pinion gear 50 (FIG. 10)that meshes with and drives a pair of driven gears 49 of drive unit 46.Driven gears 49 are affixed to a pair of drums 51, 52 (FIGS. 8, 9) whichpull the wire rope as described hereafter. Drive unit 46 can be operatedto pay out or reel in the wire rope. This type of winch drivearrangement is generally known in the art.

As shown in FIGS. 7 through 11, winch mechanism 27 of the inventionserves a dual purpose. It operates the main capstan drive 46 to pull thecable with attached mole and burst a pipe, and also is used to raise andlower the telescoping mast. FIG. 8 illustrates the mast assembly 32 andfoot assembly 34 in stowed positions prior to use.

Cable 55 is wound about drums 51, 52 and its leading end comes off offront drum 52 as shown and enters a pivot mechanism 53. Pivot mechanism53 includes a pair of aligned, spaced vertical mounting plates 54 thatare rigidly secured to frame 22. Each plate 54 has an array of spacedholes 56. A rectangular reinforcing plate 57 is mounted to two adjoiningholes 56 by means of a pin 58 and an axle 59. As shown in FIG. 11, thesestructures are duplicated on the left and right side of the device sothat the cable may pass through the center. Thus there are two axles 59,one mounted on each plate 54.

A pivoting bracket 61 includes left and right side plates 62, 63 unitedby a cylindrical crossbar 64. Each plate 54 has a bearing sleeve 66 inwhich one of the axles 59 turns. A pair of projections 67 extend fromone each of plates 62, 63 and are rigidly secured at their ends to abearing sleeve 68 oriented at a right angle relative to crossbar 64 andaxles 59. Projections 67 extend rearwardly when the mast is stowed as inFIG. 8, and extend downwardly when the mast is deployed as in FIG. 9. Anear 69 of frame 61 extends rearwardly and downwardly in the positionshown in FIG. 8. Ear 69 is connected to the end of a hydraulic cylinder71 that is attached to frame 22 and receives fluid in the same manner asthe other devices described above.

A swing frame 72 is mounted on pivoting bracket 61 by means of bearingsleeve 68. Swing frame 72 includes a pair of symmetrical side plates 73,a rear end wall 74 and a pair of lateral support plates 76, 77 than spanplates 73 to form a generally rectangular structure. Plates 76, 77 havealigned holes therein in which a pair of end caps 78, 79 are mounted andthen welded into place. Through holes 81, 82 of end caps 78, 79 arealigned with the interior of bearing sleeve 68, and a pivot 83 isinserted therein to complete the assembly. Pivot pin 83 is secured toouter end cap 81 by any suitable means, such as a crosswise bolt (notshown) inserted through aligned apertures 85 in pin 83 and end cap 81. Afurther axle 84 spans plates 76, 77 at an intermediate location and hasa sheave 86 rotatably mounted thereon for guiding the cable 55 asexplained hereafter. By means of pivot 83, swing frame 72 can swing fromside to side relative to bracket 61. Swing frame 72 and pivot mechanism53 together provide the mounting assembly by which the top mast section92 is secured to the frame 22.

Swing frame 72 further has a latch mechanism 93 mounted on rear wall 74.Latch mechanism 93 includes a generally L-shaped latch 90 pivotallymounted at one end to a tab 87 extending outwardly from rear wall 74.Latch 90 extends through a hole 88 in wall 74, which is strengthened bya reinforcing strip 89, and into an aligned hole 91 in an outer mastsection 92. By this means, sliding movement of mast section 92 relativeto swing frame 72 is prevented unless latch 76 is lifted, to permitremoval or adjustment of outer mast section 92. Mast section 92 isnormally mounted so that the last in the series of holes 91 is engagedby latch 76, as shown in FIG. 9.

Mast assembly 32 includes two or more telescoping mast sections, in thisexample upper mast section 92, middle mast section 94, and lower mastsection 96. These mast sections are generally hollow rectangular steelbeams of progressively decreasing dimensions in cross-section eachhaving sufficient strength to support the cable tension during pipebursting. FIGS. 13-16 illustrate an upper joint 95 formed by masts 92,94. An outer wall 101 of upper mast 92 has a series of holes 91 thereinalong with reinforcing strip 89, which comprises a contiguous series ofhourglass-shaped sections with holes 91 located through the widenedportions. A pair of side walls 102 have holes 103 near the lower endsthereof through which a pair of stops 104 are secured, such as by boltsmounted in aligned holes 106. As shown in FIG. 16, an upper end portion107 of middle mast 94 is widened, as by welding additional plates 108thereon in position to engage stops 104 when mast 94 is fully extended.Stops 104 and plates 108 prevent masts 92, 94 from becoming disengagedunless stops 104 are first removed. A rear wall 100 has a lengthwisegroove 105 therein, and mast sections 94 and 96 have similar groovestherein to accommodate sheave 86, which protrudes part way inside of themast assembly (see FIG. 8). Preferably, these grooves 105 extend morethan half the length of each mast section 92, 94, 96. This permitsrepositioning of the mast assembly 32 in a greater variety of positionswhile permitting cable 55 free access to the interior of the mastassembly 32. As shown in FIG. 8, grooves 105 extend from an upper end ofmast sections 92, 94, 96 to the point where sheave 86 is positioned whenthe mast assembly 32 is in its stowed position.

In the case of an unusually shallow pipe line that is only a few feetbeneath the surface, conventional mast assemblies in fixed lengthsections may be too long to access the pipeline. According to theinvention, latch 90 may be actuated and the position of mast assembly 32relative to swing frame 72 may be adjusted upwardly so that latch 90engages one of the holes 91 further down than the top one shown. In thismanner the mast assembly can be used to access a shallow pipeline at adepth that is less than the length of the outermost (top) mast section92.

An outer wall 109 of middle mast 94 has a series of holes 110 thereinwhich can be moved into alignment with holes 91. A latch mechanism 111similar to latch mechanism 74 includes a pivoting latch 112 mounted nearthe lower end of outer wall 101. When mast 94 is fully extended, latch112 is manually moved into engagement with aligned holes 91, 110 so thatthe mast sections 92, 94 are secured in the extended position. The jointbetween lower mast section 96 and middle section 94 is secured in thesame manner using a latch 113.

Referring to FIGS. 17-27, foot assembly 34 is secured at the lower endof lower mast section 96. Foot assembly 34 includes a generally fanshaped frame 121 including a pair of parallel vertical plates 122leading up to a horizontal top plate 123 that has a pair of rearwardlyprotruding rounded corners 124. A central cylindrical boss 126 extendsup from top plate 123 into a socket 127 in the lower end of mast section96. The lower end of mast section 96 has a circular flange 128positioned to abut face to face with plate 123 when boss 126 is fullyinserted into socket 127. A pair of hooks 129 are mounted on brackets131 attached below plate 123 on opposite sides of plate 123. Hooks 129are pivotally mounted by pins in lower holes 132 through brackets 131.In this manner, hooks 129 can be manually moved up and over the top sideof flange 128 and secured therein by a second pair of pins insertedthrough upper holes 133 in brackets 131. Once so secured, foot assembly34 hangs from lower mast section 94. Preferably there is a slightclearance between flange 128 and plate 123, permitting swiveling of footassembly 34 with boss 126 turning inside of socket 127.

As shown in FIG. 21, a large transverse axle 136 has a pair of end caps137, 138 welded to its ends, which end caps are in turn secured to frame121. One or more bearings 139 are mounted to support an upright sheave142 rotatably on axle 136. Sheave 142 is the last of a series of sheavesused for guiding the cable, as explained hereafter. Frame 121 also has apair of aligned holes 130 at the lower corners of plates 122 in which apin may be removably mounted to retain the cable inside frame 121. Sucha pin may also be used as a connection point for the cable when raisingand lowering the mast, or such a connection point may be located at anyconvenient location elsewhere on foot assembly 34 or lower mast section94.

Foot assembly 34 includes a pair of extendable, foldable feet 143extending laterally from one side thereof. Feet 143 are positionedsymmetrically on either side of sheave 142 and define an angle of up to180° relative to one another, more typically from 20°-90°. Each foot 143comprises a pair of telescoping, front and rear legs 144, 146. Each rearleg 146 is pivotally mounted in a U-shaped side channel 147 of frame121. Legs 144, 146 have rows of alignable holes 148, 149 along the topand bottom walls thereof whereby the length of each foot 143 may beadjusted using a pin 151 through a pair of aligned holes 148, 149. Pin151 and other similar other similar pins shown may be secured usingcotter pins.

The distal end of front leg 144 may comprise a solid rod 152 having areaction plate 153 mounted thereon for bracing against the wall of ahole. Plates 153 may be mounted by means of ball joints 154 that permitswiveling of plate 153 in one or more directions relative to rod 152. Acover 161 spans and supports channels 147 and has a central notch 162through which the cable comes off of sheave 142. Cover 161 is attachedto plates 122 at attachment slots 162, and has wings 163 which passunderneath channels 147 as shown in FIG. 17.

Feet 143 are locked into horizontal positions by means of pins 156mounted in holes 157 along the upper sides of each channel 147. In orderto fold up feet 143 for storage, pins 156 are removed and feet 143 arepivoted upwardly by almost 90° (FIG. 23). Once in this position, pins156 are replaced in a second set of holes 158 and corresponding holes159 through rear legs 146 to hold feet 143 in their stowed positions.

An optional side brace assembly 171 may be provided as needed to bracefoot assembly 34 against one side wall of the manhole or otherexcavation. Side brace comprises a beam 172 having upper and lower rowsof spaced attachment holes 173 therein. A removable foot assemblyincludes a reaction plate 174 and a socket 176 in which a distal end ofbeam 172 is inserted and secured with a pin 177. The other end of beam172 is inserted through a side opening 178 in frame 121 such that itpasses over the top of the adjoining leg 146 when in the deployedposition. A pin 179 passes through a pair of holes 173 and throughcorresponding holes in top plate 123 and an intermediate plate 181 offrame 121 (see FIGS. 17, 19). In this manner, the length of side brace171 may be adjusted as needed, and different reaction plate devices canbe used. When it is desired to fold up foot assembly 34 to its stowedposition, brace assembly 171 can be completely removed by pulling a pin179 and removing beam 172 from opening 178.

Referring again to FIGS. 8-9, the wire rope or cable 55 comes off ofdrums 51, 52 at an upper side of drum 52 and is wound about crossbar 64.It then passes upwardly into swing frame 72 in tangential contact withsheave 86, then forwardly along the inside of lower mast section 96,which is the innermost mast section when the machine is in its stowedposition. Cable 55 passes through the center of cylindrical boss 96 andinto foot assembly 34, where it is wound about sheave 142 and comes outthrough notch 162. At this point, the free end of cable 55 can besecured in any desired manner, e.g. bolted to an eye mounted for thatpurpose, or simply tied about the mast assembly in a secure manner.Cable 55 passes between the side plates of pivot mechanism 53 and swingframe 72 and is confined therebetween.

When it is time to deploy the mast, the free end cable 55 is firstsecured to foot assembly 34, such as by means of a pin 135 set throughholes 130 (see FIG. 24 showing pin 135 in phantom). In the alternative,hardware at the distal end of the cable 55 will normally prevent its endfrom fitting between pin 135 and sheave 141. If pin 135 if left inplace, then no special point of attachment for the free end of cable 55is needed in order to raise and lower the telescoping mast.

Upon retraction of cylinder 71, bracket 61 pivots about axles 59,carrying with it swing frame 72, mast assembly 32 and foot assembly 34.This moves mast assembly 32 from a horizontal to a vertical position.Lowermost latch 113 is then unfastened, and lower leg section 96 islowered as cable 55 is gradually payed out. The cable acts against theforce of gravity, assuring that mast section 96 is lowered at acontrolled pace. The process continues until mast section 96 is fullyextended, at which time latch 113 is reset and second latch 112 isreleased so that middle mast section 94 begins to extend from the insideof top mast section 92. When the lower and middle mast sections arefully extended, latch 112 is reset to lock the extended mast in positionas shown in FIG. 12.

Foot assembly 34 may then be deployed at the bottom of the hole byunfolding and setting feet 143, and setting side brace 171 if needed.Side brace 171 is particularly useful when the machine is positioned onuneven terrain such as a hill side, and needs to be braced againstlateral movement of the mast. Side brace 171 is also used in situationswhere it is necessary to set up the telescoping mast 32 at an angleother than 90° in order to reach the pipeline, which may be offset fromthe manhole entrance. It is known in the art in such situations tomanually set up a winch mast and brace it at an angle. The presentinvention permits this with a mast assembly that does not need to bedeployed manually. Pivot 83 permits mast assembly 32 of the invention toswing from side to side, and axle 59 permits mast assembly 32 of theinvention to swing from front to back while remaining secured to frame22. Thus, once mast assembly 32 is extended into a manhole having anoffset pipeline, it is then pivoted at its top end up to about 15degrees in either direction from side to side, and 15 degrees in eitherdirection from front to back. Once the bottom end is at the desiredlocation near the offset pipeline entrance, foot assembly 34 is thendeployed. Side brace 171 is then used to brace mast assembly 32 in itsangled position.

Feet 143 are extended so that reaction plates 151 engage the wall of thehole adjoining the existing conduit. As part of the process of bracingmast 32, hydraulic cylinder 71 is set to float to prevent undesirableloading on mast 32. The cable can then be extended from foot assembly 34and the free end can be fed through the existing pipeline in aconventional manner. A mole is attached to the free end of the cable atthe other end of the pipeline to be replaced, and the winch unit 21 isthen used in its pulling mode to pull the mole and trailing plasticreplacement through the existing pipeline. Once the burst is completed,the mole is detached and the cable reattached to foot assembly 34. Sidebrace 171 is removed and feet 143 are collapsed, pivoted upright andsecured in position. Latches 112, 113 are unlocked either at the sametime or 113 first followed by 112, in the reverse of the deploymentprocedure. Winch mechanism 27 is then actuated to reel in cable 55,which lifts lower mast section 96 sliding it upwardly inside of mastsection 94. The process is then repeated with mast sections 92, 94 untilthe mast assembly 32 has returned to a fully collapsed state. At thispoint, cylinder 71 is extended, reversing the previous motion andreturning mast assembly 32 to its horizontal stowed position. It isoften desirable to remove the mast assembly from the hole prior toremoving the mole, which may be a relatively small bursting head or alarger device such as an impact bursting tool such as a pneumatichammer.

At this point, an optional latch mechanism 33 provided on top of vehiclehousing 26 may be used to secure the collapsed mast assembly 32. Asshown in FIGS. 5, 12A, and 12B, latch mechanism 33 includes an L-shapedbracket 192 mounted on frame 22 and a movable latch 193. Bracket 192comprises a pair of parallel plates 194 profiled to form a cradle 196defined by upper, lower and side edges of plates 194. Latch 193 extendsoutwardly between plates 194 ending in a handle 197. The inner end oflatch 193 is pivotally mounted on a crosspin 198 secured to bracket 192.Latch has an upwardly extending finger 199 positioned to extend upwardlyinto the middle of cradle 196. Once mast assembly 32 is in itshorizontal position, it is resting in cradle 196 with latch 193 in adown position. Latch 193 is then raised, moving it into engagement withmast assembly 32 such that finger 199 in inserted into grooves 105,retaining mast assembly 32 until latch 193 is lowered. Latch 193 may besecured in a raised position by any suitable means, such as a spring 201that biases latch 193 towards the raised position, or a mechanicallocking mechanism. Finger 199 may also be relocated inwardly to engagean outer wall of mast assembly, trapping it on the fourth side notcovered by cradle 196.

Use of the winch's wire rope to raise and lower the telescoping mast aswell as the down hole sheave (leg assembly) eliminates the need for anadditional piece of equipment to accomplish this. However, it will beunderstood by those skilled in the art that other means could beprovided for raising and lowering the mast without using the main winchfor this purpose. For example, the upper two mast sections 92, 94 andthe swing frame 72 can each be provided with an automotive-style jackmechanism as shown in FIGS. 28-30. Swing frame 72 has a bracket 211 andjack mechanism 212 on its side wall. Jack mechanism 212 engages a seriesof holes 213 provided on all three mast sections, moving from one holeto the next each time the jack mechanism 212 is actuated with a lever214. The arrangement for masts 94, 96 is identical to that shown formasts 92, 94 in FIGS. 29, 30. This embodiment is viable but is not asdesirable as a powered system which can extend and collapse thetelescoping mast automatically.

FIGS. 31-32 illustrate another alternative embodiment wherein amechanical winch similar to a conventional boat trailer winch is used toraise and lower the mast. The winch mechanism 221 includes a crank 222that is turned manually to raise and lower the telescoping mastsections. It may be conveniently mounted as shown so that a secondarycable 223 runs down near a side or corner of the telescoping mast, awayfrom the main cable 55, which is much thicker. An eye at the end ofsecondary cable 223 may be permanently mounted on pin 135, or at anyother convenient location.

The apparatus of the invention provides a number of advantages duringthe bursting process. The invention eliminates handling of the mastsections much as a bucket type man-lift truck eliminates the need tohandle ladders when servicing utility poles. The mast must extend to thebottom of the manhole, typically this is in the range of 6 to 20 feetfrom the surface. As a typical winch of the size and type used in pipebursting is approximately 9 feet long not including it's trailer tongue,the mast cannot conveniently be any longer than 9 feet. To achieve thedepths required, the mast must have sections. By telescoping thesesections, placing a larger one over a smaller one and again over asmallest mast, the design can be achieved. In practice, it has beenfound that this telescoping mast is best pivoted about an axis at therear of the winch for storage. By laying on top of the winch for travel,the overall height is kept considerably below the 9 foot mast height, afeature useful for access to tight job sites as well as enhancing safetyduring transport.

The winch of the invention is backed up to a manhole, the engine isstarted, and the operator toggles a switch after unlatching the mastfrom its storage cradle. The switch trips a hydraulic valve allowingactuation of the cylinder that pivots the mast into the uprightposition. Upon achieving that, the first latch is disengaged and theinner mast is lowered by feeding wire rope off the winch storage drum.When the mast has reached it's full extension, the first latch isengaged and the process repeated for the second section. When thedesired depth has been achieved, the second latch is engaged. Theengagement of the latches makes the telescoping mast capable of beingstructurally loaded by the cable tension. This setup process took oneoperator approximately three minutes. The old mast design wherein themast sections had be lowered and assembled in the hole took three men atotal of three man hours of physical effort and a second piece of mobileequipment to lift the mast assembly.

Unique aspects of the invention include the use of a telescoping mast toachieve great depth (deployed mast length), but with reasonable lengthin the collapsed position for storage and transport. Pivoting of thecollapsed mast assembly further enhances transportability. Use oflatches on the mast provides column compression stiffness that allowsthe mast to be loaded structurally. The invention as such includes theforegoing, as well as those defined more specifically in the claims thatfollow.

1. A portable winch, comprising: a mounting frame positionable at a topopening of a hole; a mast including at least upper and lower mastsections; a swing frame connected by a pivot to the mounting frame andpositioned to pivot the mast between a first storage position and asecond operating position from which the mast is extendable into thehole; a power winch mounted on the mounting frame to extend and retracta cable about a sheave connected to the lower mast section; and amechanism on the mounting frame that gradually raises and lowers themast relative to the mounting frame into and out of the hole.
 2. Thewinch of claim 1, wherein the mast sections are telescoping, and theraising and lowering mechanism comprises a second winch positioned forcollapsing and extending the telescoping sections.
 3. The winch of claim1, wherein the mechanism for raising and lowering the mast is a powerdriven mechanism.
 4. The winch of claim 3, wherein the mechanism forraising and lowering includes the power winch mounted on the mountingframe and a releaseable connector between the lower mast section and thecable.
 5. The portable winch of claim 1, A portable winch, comprising: amounting frame positionable at a top opening of a hole; a mast includingat least upper and lower mast sections; a swing frame connected by apivot to the mounting frame and positioned to pivot the mast between afirst storage position and a second operating position from which themast is extendable into the hole; a power winch mounted on the mountingframe to extend and retract a cable about a sheave connected to thelower mast section; and a mechanism on the mounting frame that graduallyraises and lowers the mast relative to the mounting frame into and outof the hole, wherein the upper mast section is slidably mounted on theswing frame, the winch further comprising a latch for securing the uppermast section in the swing frame at one of a plurality of predeterminedlocations.
 6. The portable winch of claim 5, wherein the upper mastcomprises a series of holes wherein the latch may be selectively engagedand a reinforcing strip for reinforcing the mast around one or more ofthe holes.
 7. The portable winch of claim 1, wherein the mounting framecomprises a wheeled trailer having a plurality of extendable jacks forsupporting the mounting frame.
 8. The portable winch of claim 1, furthercomprising a powered pivoting mechanism configured to swing the mast andswing frame about the pivot between the storage position and theoperating position.
 9. The portable winch of claim 8, wherein thepowered pivot mechanism comprises a hydraulic cylinder having one endsecured to the mounting frame and the other end secured to the swingframe.
 10. A method for deploying a portable winch comprising a mountingframe, a mast including at least two top and bottom mast sections, whichmast is mounted to the mounting frame by a pivot mechanism, and a powerwinch mounted on the mounting frame to extend and retract a cable abouta sheave connected to the bottom mast section, comprising: positioningthe mounting frame of the portable winch at a top opening of a hole;pivoting the mast by the pivot mechanism from a horizontal position to avertical position; lowering the mast into the hole; securing the mast inthe hole for horizontal pulling using a pulling cable wound over asheave; after use of the power winch, unsecuring the mast so that themast can be removed from the hole; and raising the mast from the hole byoperating a mechanical mast control system that gradually pulls thelower mast section upwardly relative to the mounting frame.
 11. Themethod of claim 10, further comprising, after raising the mast from thehole, pivoting the mast sections from a vertical position to ahorizontal position using the pivot mechanism.
 12. The method of claim10, wherein the mast control system comprises a second winch mounted onthe mounting frame.
 13. The method of claim 10, wherein the mastcomprises telescoping sections that are extended and retracted by themast control system.
 14. The method of claim 10, wherein the mastcontrol system is power-driven.
 15. The method of claim 14, wherein themast control system includes the power winch mounted on the mountingframe and a releaseable connector between the lower mast section and thecable.
 16. The method of claim 10, wherein lowering the mast into thehole comprises operating the mechanical mast control system to graduallylower the bottom mast section.
 17. The method of claim 10, whereinpivoting the mast from a horizontal position to a vertical position iscarried out using a powered pivot mechanism.